We Keep Coding

How do I get the Value out of my Class into my TextViewField

At the moment I am trying to make an Android App with Android Studio with GET and POST data into/from an API.
My problem at the moment is that I want to have the response of the POST request displayed in my app. For this I made the TextView TW_Rueckgabe. I also made another Method just for this so it can Display the Request which is
public String returnString() {
return fetching_data;
}
but the response is not saved in TW_Rueckgabe.
MainActivity.java
final TextView[] TW_Rueckgabe = {findViewById(R.id.textViewRueckgabe)};
Button sendBtn = findViewById(R.id.sendBtn);
sendBtn.setOnClickListener(v -> {
String POST_url = "http://dphost.ddns.net:1573/cool/post.php";
String requestData = "data=" + TW_Benutzername.getText().toString();
POSTRequestTask test = (POSTRequestTask) new POSTRequestTask().execute(POST_url, requestData);
TW_Rueckgabe[0].setText(test.fetching_data);
});
POSTRequestTask Class:
class POSTRequestTask extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String... params) {
String url = params[0];
String requestData = params[1];
String response = "";
try {
URL obj = new URL(url);
HttpURLConnection con = (HttpURLConnection) obj.openConnection();
// add request header
con.setRequestMethod("POST");
con.setDoOutput(true);
// add request data
DataOutputStream wr = new DataOutputStream(con.getOutputStream());
wr.writeBytes(requestData);
wr.flush();
wr.close();
int responseCode = con.getResponseCode();
System.out.println("\nSending 'POST' request to URL : " + url);
System.out.println("Response Code : " + responseCode);
BufferedReader in = new BufferedReader(
new InputStreamReader(con.getInputStream()));
String inputLine;
StringBuffer responseBuffer = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
responseBuffer.append(inputLine);
}
in.close();
response = responseBuffer.toString();
} catch (IOException e) {
e.printStackTrace();
}
return response;
}
#Override
protected void onPostExecute(String result) {
// print result
System.out.println("\n\n\n" + result + "\n\n\n");
fetching_data = result;
}
public String returnString() {
return fetching_data;
}
}
I tried to make a new Object and then save the Variable from the Object, didn't work.

interface Callback {
void onResponse(String response);
}
MainActivity {
private Callback callback = new Callback() {
#Override
void onResponse(String response) {
TW_Rueckgabe[0].setText(test.fetching_data);
}
}
sendBtn.setOnClickListener(v -> {
String POST_url = "http://dphost.ddns.net:1573/cool/post.php";
String requestData = "data=" + TW_Benutzername.getText().toString();
POSTRequestTask test = new POSTRequestTask(callback).execute(POST_url, requestData);
});
}
class POSTRequestTask(Callback callback) extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String... params) {
// do your request as you're doing now and return the result
}
#Override
protected void onPostExecute(String result) {
// callback interface method call here
callback.onResponse(result)
}
}

android returning a JSONObject from a static method + network on main thread

I have this method which is giving a network on main thread. I want to make this api call on a separate thread using asynctask.
However, the business logic prohibits me to use non static methods. The code is:
public static JSONObject acceptOrder(String orderId, Integer loadsToAccept) throws IOException{
BufferedReader reader = null;
JSONObject resultOrder = null;
AsyncTask asyncTask = new AsyncTask() {
#Override
protected Object doInBackground(Object[] objects) {
return null;
}
};
HttpURLConnection conn = (HttpURLConnection) new URL(GlobalConfig.getInstance().GetGoVulcanConfig().getUrl() + "/api/Order/ProcessAcceptedOrder?acceptedLoads=" + loadsToAccept + "&haulerId=" + GlobalConfig.getInstance().GetGoVulcanConfig().getHaulerId() + "&orderId=" + orderId).openConnection();
conn.setDoOutput(true);
//conn.setFixedLengthStreamingMode(jsonString.length());
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/json");
conn.setRequestProperty("Accept","application/json");
InputStream inputStream = conn.getInputStream();
StringBuffer buffer = new StringBuffer();
if (inputStream == null) {
// Nothing to do.
return null;
}
reader = new BufferedReader(new InputStreamReader(inputStream));
String inputLine;
while ((inputLine = reader.readLine()) != null)
buffer.append(inputLine);
if (buffer.length() == 0) {
// Stream was empty. No point in parsing.
return null;
}
try {
resultOrder = new JSONObject(buffer.toString());
}catch (JSONException ex){
Log.d(ex.getMessage(), "acceptOrder: ");
}
conn.disconnect();
reader.close();
return resultOrder;
}
How can I do this?

This is the form that i do to request POST or GET, I hope can help you
1) I have my class with all the request
public class RequestManager {
public static class requestPostExample extends AsyncTask<String, Void, String>{
Context context;
int exampleId;
String exampleData;
//interface to get the response in the activity
Public AsynkTaskRespone response = null;
public requestPostExample(Context context, int exampleID, String exampleData){
this.context = context;
this.exampleId = exampleID;
this.exampleData = exampleData;
}
#Override
protected String doInBackground(String... params) {
try {
String urlString = "yourUrl";
URL url = new URL(urlString);
//the variables and data you want to send by POST
String postData = "exampleID="+exampleID+"&exampleData="+exampleData;
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestMethod("POST");
OutputStream os = connection.getOutputStream();
os.write(postData.getBytes());
StringBuilder responseSB = new StringBuilder();
int result = connection.getResponseCode();
BufferedReader br;
// 401 - 422 - 403 - 500
if (result == 401 || result == 422 || result == 403 || result == 404 || result == 500){
br = new BufferedReader(new InputStreamReader(connection.getErrorStream()));
}else {
br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
}
while ( (JSON_STRING = br.readLine()) != null)
responseSB.append(JSON_STRING+ "\n");
// Close streams
br.close();
return responseSB.toString().trim();
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
#Override
protected void onPostExecute(String result) {
Log.d("Result:", result);
//send the result to interface;
response.resultPostExample(result);
}
}
2) Here is the Interface
public interface AsynkTaskRespone {
void resultPostExample(String result);
}
3) Now in the activity
public class MainActivity extends AppCompatActivity implements AsynkTaskResponse {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Start Request
RequestManager.requestPostExample requestPostExample = new RequestManager.requestPostExample(this, exampleID, exampleData);
requestPostExample.response = this;
requestPostExample.execute();
}
#Override
public void resultPostExample(String result){
//here you get the result of the asynktask
}
}

Run code in AsyncTask stucking UI

I'm trying a copule of days to figure it out, without success,
Target: get use country by IP using asyncTask without stucking UI, and save it into string parm.
Problem: The UI doen't move until the asyncTask finish it job :/
MainActivity ,onCreate method:
.......
JSONObject jsonObject;
try {
jsonObject = new getJSONObjectFromURL(LoginActivity.this).execute("http://ip-api.com/json").get();
if (jsonObject != null) {
if (!jsonObject.getString("status").equals("success"))
throw new InterruptedException();
Log.d(TAG, "onCreate: jsonObject.tostring:" + jsonObject.toString());
countryLocation = jsonObject.getString("country");
Log.d(TAG, "onCreate: countryByIP " + countryLocation);
}
if (!isNetworkAvailable()/* || countryLocation == null*/)
Toast.makeText(MainActivity.this, "Please enable data.", Toast.LENGTH_SHORT).show();
//in button click redo all that code for no internet connection,.
} catch (InterruptedException | ExecutionException | JSONException e) {
e.printStackTrace();
}
asyncTask:
public class getJSONObjectFromURL extends AsyncTask<Object, Object, JSONObject> {
private Context context;
public getJSONObjectFromURL(Context context) {
this.context = context;
}
#Override
protected JSONObject doInBackground(Object... params) {
HttpURLConnection urlConnection = null;
URL url = null;
try {
url = new URL((String) params[0]);
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setReadTimeout(10000 /* milliseconds */);
urlConnection.setConnectTimeout(15000 /* milliseconds */);
urlConnection.setDoOutput(true);
urlConnection.connect();
BufferedReader br = new BufferedReader(new InputStreamReader(url.openStream()));
String jsonString;
StringBuilder sb = new StringBuilder();
String line;
while ((line = br.readLine()) != null) {
sb.append(line + "\n");
}
br.close();
jsonString = sb.toString();
return new JSONObject(jsonString);
} catch (JSONException | IOException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(JSONObject result) {
//Update the String..
}
}
Everything works perfect, i get the Json, able to read the Country from it, but MainActivity waiting for the onPostExecute to continue.

You are running your AsyncTask in a synchrounous state.
jsonObject = new getJSONObjectFromURL(LoginActivity.this).execute("http://ip-api.com/json").get();
By calling get() you are waiting until the Task has finished it's job. Do not use get() if you want to have a truly asynchronous process. You can use a callback to get notified.

Why I am getting null pointer exception even though there is value show when println?

This is a function of class A where i pass my value to a class name confirm to its register function.
private void registerOrder() {
confirm.register(id);
}
This is class confirm. In this class i have plan to post data inside the server. There is no mistakes in the url. I have println this code " System.out.println("wei" + getPostDataString(postDataParams));" and i have gotten my value. But the system says null pointer. Is there any mistakes in other pats of the code?
public class confirm {
private static final String REGISTER_URL =
"http://192.168.43.214/apexStore2/confirm.php";
public static void register(String id) {
class RegisterUser extends AsyncTask<String, Void, String> {
ProgressDialog loading;
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
loading.dismiss();
}
#Override
protected String doInBackground(String... params) {
HashMap<String, String> data = new HashMap<>();
data.put("product_id",params[0]);
String result = sendPost(REGISTER_URL,data);
return result;
}
}
RegisterUser ru = new RegisterUser();
ru.execute(String.valueOf(id));
}
public static String sendPost(String requestURL,
HashMap<String, String> postDataParams) {
URL url;
String response = " ";
try {
url = new URL(requestURL);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type",
"application/x-www-form-urlencoded");
conn.setRequestProperty("Content-Length", "" +
Integer.toString(getPostDataString(postDataParams).getBytes().length));
conn.setRequestProperty("Content-Language", "en-US");
conn.setReadTimeout(15000);
conn.setConnectTimeout(15000);
conn.setDoInput(true);
conn.setDoOutput(true);
OutputStream os = conn.getOutputStream();
BufferedWriter writer = new BufferedWriter(
new OutputStreamWriter(os, "UTF-8"));
writer.write(getPostDataString(postDataParams));
System.out.println("wei" + getPostDataString(postDataParams));
writer.flush();
writer.close();
os.close();
int responseCode=conn.getResponseCode();
if (responseCode == HttpsURLConnection.HTTP_OK) {
BufferedReader br=new BufferedReader(new
InputStreamReader(conn.getInputStream()));
response = br.readLine();
}
else {
response="Error Registering";
}
} catch (Exception e) {
e.printStackTrace();
}
return response;
}
private static String getPostDataString(HashMap<String, String> params)
throws UnsupportedEncodingException {
StringBuilder result = new StringBuilder();
boolean first = true;
for(Map.Entry<String, String> entry : params.entrySet()){
if (first)
first = false;
else
result.append("&");
result.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
result.append("=");
result.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
}
return result.toString();
}
}

You have an instance variable, which is never assigned to:
ProgressDialog loading;
and it is used in
protected void onPostExecute(String s) {
super.onPostExecute(s);
loading.dismiss(); // expect NPE
}

Reading your code I supose the null pointer exception appears when you call confirm.register(id).
If you want to use a class in a static manner you need to declare it as a final class:
public final class confirm {...}
For you it should work. Nevertheless you can also solve your problem without using the final identifier by creating an instance of your class:
confirm conf = new confirm();
conf.register(id);
I also have seen that your class name begins with a lowercase letter. It is recomended to create the classes names begining with a capital letter.
If it doesn't solve your error please, pastate the error information here.

Show progress bar while downloading JSON - Android

I am downloading a very huge JSON and it takes a lot of time.
I want to show the percentage of data I have downloaded.
I searched and found how to display progress if downloading a file but not JSON.
Here is how I am downloading JSON
private String getStringFromURL(String url) {
String string = null;
try {
HttpClient client = new DefaultHttpClient();
url = url.replace(" ", "%20");
url = url.replace("|", "%7C");
HttpGet get = new HttpGet(url);
HttpResponse response = client.execute(get);
if (response.getStatusLine().getStatusCode() == 200) {
String result = EntityUtils.toString(response.getEntity(),
HTTP.UTF_8);
if (result.toLowerCase().contains("invalid"))
return null;
result = result.replace("\r", "");
result = result.replace("\n", "").replace("\t", "\\t")
.replace("\b", "\\b").replace("\f", "\\f")
.replace("&", "\\&").replace("\'", "\\'")
.replace(";", "\\;").replace("?", "\\?")
.replace("*", "\\*");
string = result;
}
} catch (Exception e) {
e.printStackTrace();
}
return string;
}

You better to use AsyncTask to download data. There is a sample code below. I did not test it but it should work.
private class FetchJsonTask extends AsyncTask<Void, Void, String> {
private ProgressDialog progressDialog;
private Context context;
public FetchJsonTask(Context context) {
this.context = context;
}
#Override
protected void onPreExecute() {
// set up progress dialog
progressDialog = new ProgressDialog(context);
progressDialog.setIndeterminate(true);
progressDialog.setMessage("Please wait...");
// show it
progressDialog.show();
}
#Override
protected String doInBackground(Void... params) {
// These two need to be declared outside the try/catch
// so that they can be closed in the finally block.
HttpURLConnection urlConnection = null;
BufferedReader reader = null;
// Will contain the raw JSON response as a string.
String jsonStr = null;
try {
// Construct the URL somehow
URL url = createURL();
// Create the request to MuslimSalat.com, and open the connection
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.connect();
// Read the input stream into a String
InputStream inputStream = urlConnection.getInputStream();
StringBuffer buffer = new StringBuffer();
if (inputStream == null) {
// Nothing to do.
return null;
}
reader = new BufferedReader(new InputStreamReader(inputStream));
String line;
while ((line = reader.readLine()) != null) {
// Since it's JSON, adding a newline isn't necessary (it won't affect parsing)
// But it does make debugging a *lot* easier if you print out the completed
// buffer for debugging.
buffer.append(line + "\n");
}
if (buffer.length() == 0) {
// Stream was empty. No point in parsing.
return null;
}
jsonStr = buffer.toString();
} catch (IOException e) {
Log.e(LOG_TAG, "Error ", e);
// If the code didn't successfully get the data, there's no point in attemping
// to parse it.
return null;
} finally{
if (urlConnection != null) {
urlConnection.disconnect();
}
if (reader != null) {
try {
reader.close();
} catch (final IOException e) {
Log.e(LOG_TAG, "Error closing stream", e);
}
}
}
return jsonStr;
}
#Override
protected void onPostExecute(String jsonString) {
// jsonString is your result use it somehow.
Log.d(LOG_TAG, "Json result: " + jsonString);
// dismiss the progress because downloading process is finished.
progressDialog.dismiss();
}
}
You can call it from your activity, fragment etc.
FetchJsonTask fetchJsonTask = new FetchJsonTask(context);
fetchJsonTask.execute();